1/*
2 * mpls tunnels An implementation mpls tunnels using the light weight tunnel
3 * infrastructure
4 *
5 * Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 */
13#include <linux/types.h>
14#include <linux/skbuff.h>
15#include <linux/net.h>
16#include <linux/module.h>
17#include <linux/mpls.h>
18#include <linux/vmalloc.h>
19#include <net/ip.h>
20#include <net/dst.h>
21#include <net/lwtunnel.h>
22#include <net/netevent.h>
23#include <net/netns/generic.h>
24#include <net/ip6_fib.h>
25#include <net/route.h>
26#include <net/mpls_iptunnel.h>
27#include <linux/mpls_iptunnel.h>
28#include "internal.h"
29
30static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
31 [MPLS_IPTUNNEL_DST] = { .type = NLA_U32 },
32 [MPLS_IPTUNNEL_TTL] = { .type = NLA_U8 },
33};
34
35static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
36{
37 /* The size of the layer 2.5 labels to be added for this route */
38 return en->labels * sizeof(struct mpls_shim_hdr);
39}
40
41static int mpls_xmit(struct sk_buff *skb)
42{
43 struct mpls_iptunnel_encap *tun_encap_info;
44 struct mpls_shim_hdr *hdr;
45 struct net_device *out_dev;
46 unsigned int hh_len;
47 unsigned int new_header_size;
48 unsigned int mtu;
49 struct dst_entry *dst = skb_dst(skb);
50 struct rtable *rt = NULL;
51 struct rt6_info *rt6 = NULL;
52 struct mpls_dev *out_mdev;
53 struct net *net;
54 int err = 0;
55 bool bos;
56 int i;
57 unsigned int ttl;
58
59 /* Find the output device */
60 out_dev = dst->dev;
61 net = dev_net(out_dev);
62
63 skb_orphan(skb);
64
65 if (!mpls_output_possible(out_dev) ||
66 !dst->lwtstate || skb_warn_if_lro(skb))
67 goto drop;
68
69 skb_forward_csum(skb);
70
71 tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
72
73 /* Obtain the ttl using the following set of rules.
74 *
75 * LWT ttl propagation setting:
76 * - disabled => use default TTL value from LWT
77 * - enabled => use TTL value from IPv4/IPv6 header
78 * - default =>
79 * Global ttl propagation setting:
80 * - disabled => use default TTL value from global setting
81 * - enabled => use TTL value from IPv4/IPv6 header
82 */
83 if (dst->ops->family == AF_INET) {
84 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
85 ttl = tun_encap_info->default_ttl;
86 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
87 !net->mpls.ip_ttl_propagate)
88 ttl = net->mpls.default_ttl;
89 else
90 ttl = ip_hdr(skb)->ttl;
91 rt = (struct rtable *)dst;
92 } else if (dst->ops->family == AF_INET6) {
93 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
94 ttl = tun_encap_info->default_ttl;
95 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
96 !net->mpls.ip_ttl_propagate)
97 ttl = net->mpls.default_ttl;
98 else
99 ttl = ipv6_hdr(skb)->hop_limit;
100 rt6 = (struct rt6_info *)dst;
101 } else {
102 goto drop;
103 }
104
105 /* Verify the destination can hold the packet */
106 new_header_size = mpls_encap_size(tun_encap_info);
107 mtu = mpls_dev_mtu(out_dev);
108 if (mpls_pkt_too_big(skb, mtu - new_header_size))
109 goto drop;
110
111 hh_len = LL_RESERVED_SPACE(out_dev);
112 if (!out_dev->header_ops)
113 hh_len = 0;
114
115 /* Ensure there is enough space for the headers in the skb */
116 if (skb_cow(skb, hh_len + new_header_size))
117 goto drop;
118
119 skb_set_inner_protocol(skb, skb->protocol);
120 skb_reset_inner_network_header(skb);
121
122 skb_push(skb, new_header_size);
123
124 skb_reset_network_header(skb);
125
126 skb->dev = out_dev;
127 skb->protocol = htons(ETH_P_MPLS_UC);
128
129 /* Push the new labels */
130 hdr = mpls_hdr(skb);
131 bos = true;
132 for (i = tun_encap_info->labels - 1; i >= 0; i--) {
133 hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
134 ttl, 0, bos);
135 bos = false;
136 }
137
138 mpls_stats_inc_outucastpkts(out_dev, skb);
139
140 if (rt)
141 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
142 skb);
143 else if (rt6)
144 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
145 skb);
146 if (err)
147 net_dbg_ratelimited("%s: packet transmission failed: %d\n",
148 __func__, err);
149
150 return LWTUNNEL_XMIT_DONE;
151
152drop:
153 out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
154 if (out_mdev)
155 MPLS_INC_STATS(out_mdev, tx_errors);
156 kfree_skb(skb);
157 return -EINVAL;
158}
159
160static int mpls_build_state(struct nlattr *nla,
161 unsigned int family, const void *cfg,
162 struct lwtunnel_state **ts,
163 struct netlink_ext_ack *extack)
164{
165 struct mpls_iptunnel_encap *tun_encap_info;
166 struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
167 struct lwtunnel_state *newts;
168 u8 n_labels;
169 int ret;
170
171 ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
172 mpls_iptunnel_policy, extack);
173 if (ret < 0)
174 return ret;
175
176 if (!tb[MPLS_IPTUNNEL_DST]) {
177 NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing");
178 return -EINVAL;
179 }
180
181 /* determine number of labels */
182 if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
183 &n_labels, NULL, extack))
184 return -EINVAL;
185
186 newts = lwtunnel_state_alloc(struct_size(tun_encap_info, label,
187 n_labels));
188 if (!newts)
189 return -ENOMEM;
190
191 tun_encap_info = mpls_lwtunnel_encap(newts);
192 ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels,
193 &tun_encap_info->labels, tun_encap_info->label,
194 extack);
195 if (ret)
196 goto errout;
197
198 tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT;
199
200 if (tb[MPLS_IPTUNNEL_TTL]) {
201 tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]);
202 /* TTL 0 implies propagate from IP header */
203 tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ?
204 MPLS_TTL_PROP_DISABLED :
205 MPLS_TTL_PROP_ENABLED;
206 }
207
208 newts->type = LWTUNNEL_ENCAP_MPLS;
209 newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
210 newts->headroom = mpls_encap_size(tun_encap_info);
211
212 *ts = newts;
213
214 return 0;
215
216errout:
217 kfree(newts);
218 *ts = NULL;
219
220 return ret;
221}
222
223static int mpls_fill_encap_info(struct sk_buff *skb,
224 struct lwtunnel_state *lwtstate)
225{
226 struct mpls_iptunnel_encap *tun_encap_info;
227
228 tun_encap_info = mpls_lwtunnel_encap(lwtstate);
229
230 if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
231 tun_encap_info->label))
232 goto nla_put_failure;
233
234 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT &&
235 nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl))
236 goto nla_put_failure;
237
238 return 0;
239
240nla_put_failure:
241 return -EMSGSIZE;
242}
243
244static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
245{
246 struct mpls_iptunnel_encap *tun_encap_info;
247 int nlsize;
248
249 tun_encap_info = mpls_lwtunnel_encap(lwtstate);
250
251 nlsize = nla_total_size(tun_encap_info->labels * 4);
252
253 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT)
254 nlsize += nla_total_size(1);
255
256 return nlsize;
257}
258
259static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
260{
261 struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
262 struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
263 int l;
264
265 if (a_hdr->labels != b_hdr->labels ||
266 a_hdr->ttl_propagate != b_hdr->ttl_propagate ||
267 a_hdr->default_ttl != b_hdr->default_ttl)
268 return 1;
269
270 for (l = 0; l < a_hdr->labels; l++)
271 if (a_hdr->label[l] != b_hdr->label[l])
272 return 1;
273 return 0;
274}
275
276static const struct lwtunnel_encap_ops mpls_iptun_ops = {
277 .build_state = mpls_build_state,
278 .xmit = mpls_xmit,
279 .fill_encap = mpls_fill_encap_info,
280 .get_encap_size = mpls_encap_nlsize,
281 .cmp_encap = mpls_encap_cmp,
282 .owner = THIS_MODULE,
283};
284
285static int __init mpls_iptunnel_init(void)
286{
287 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
288}
289module_init(mpls_iptunnel_init);
290
291static void __exit mpls_iptunnel_exit(void)
292{
293 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
294}
295module_exit(mpls_iptunnel_exit);
296
297MODULE_ALIAS_RTNL_LWT(MPLS);
298MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
299MODULE_LICENSE("GPL v2");
300